Bionic Contact Lens Offers 'Nonretinal Stimulus' for Blind People

By Eye² Staff

Scientists are making progress with several new technologies to restoring some functional vision to blind people. The best known of these technologies, the Argus II Retinal Prosthesis System from
Second Sight, has received FDA approval and is now available to patients in the U.S.

Now Israeli scientists at Bar-Ilan University have developed a sensory substitution device in which nonretinal stimulus is used to generate input to the brain of blind people to substitute for damage or loss of retinal input. The device, which is still under development, consists of a contact lens delivering point mechanical or electrical stimulation of the corneal nerves and a camera mounted on a eyeglass frame which wirelessly transmits processed images to the contact lens, translating the visual information into tactile sensation, according to an article published earlier this year in the journal
Optical Engineering, which described how it was tested. In order to improve the spatial resolution of the constructed image, the camera will also time multiplex, compress and encode the captured image before transmitting it to the stimulating contact lens, the article said. Preliminary devices performing tactile stimulation of the fingers and of the tongue by applying point electrical stimulations were constructed and tested. Subjects were taught to "see" using the mechanical and the electrical tactile sensor.

In an interview with the Israeli newspaper Haaretz, Prof. Zeev Zalevsky, head of Electrical Engineering and Nanophotonics at Bar-Ilan University and the leader of the research team, said, "This technology is good news for humanity, especially in bringing sight to people blind from birth without requiring surgery or damaging other vital senses or organs."

The accompanying illustration shows: (a) general schematic sketch of the constructed prototypes; (b) Schematic sketch of the spectacles with the installed imaging camera; (c) Schematic sketch of the contact lens with the stimulation electrodes.